Apparatus for determining the motion of well drilling tools



UH HUM ma mam-WWW & 1mm MA Dec. 24, 1940. Y. NEAL ETAL 2,225,709

APPARATUS FOR DETERMINING THE MOTION 0F WELL DRILLING TOOLS Filed Dec. 13, 1937 5 Sheets-Sheet l INVENTOR' KoungerNeaZl BY Glen G.He,bard 66 up,

ATTORNEY IE5. WfihA5UHING (3L atrium.

Dec. 24, 1940. Y. NEAL'EIAL APPARATUS FOR DETERMINING THE MOTION OF WELL DRILLING TOOLS Filed Dec. 15,.1957 5 Sheets-Sheet 2 arm M w m N 07 M. O E h n H w zfW l 0 125. mmumm 32 123mm jijkfi g mim m;

Dec. 24, 1940. Y, NEAL Em 2,225,709

APPARATUS FOR DETERMINING THE MOTION 0F WELL DRILLING TOOLS Filed Dec. 13, 1937 5 Sheets-Sheet 3 Fig. 5

INVENTOR Kmnger Neal BY GZeLAnFGHebarcZ ATTORNEY 7 .m V b t N U N H U Wm m m n.

Dec. 24, 1940. Y. NEAL EIAL APPARATUS FOR DETERMINING THE MOTION OF WELL DRILLING TOOLS Filed Dec. 13, 1937 5 Sheets-Sheet 4 m N IODQJ w n 0 M T Cv O N T W 7W mvm Dec. 24, 1940;

APPARATUS FOR DETERMINING THE MOTION 0F WELL DRILLING TOOLS 'N m 33% S, u, 2

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. Y. NEAL ETAL Filed Dec. 13, 1937 1?) if. A L W W U U 5% 5 Sheets-Sheet 5 -INVENTOR eal G.Hebard Patented Dec. 24, 1940 APPARATUS FOR DETERMINING THE MO- TION OF WELL DRILLING TOOLS Younger Neal and Glen G. Hebard, Chicago, 111.,

assignors to The Pure Oil Company, Chicago, 111., a corporation of Ohio 1 Application December 13, 1937, Serial No. 179,476

6 Claims. (01. 73-30) This invention relates to apparatus for indicating the motion of apparatus used in production of fluids from earth bores, and is particularly concerned with apparatus for indicating the movement of the drilling bit in percussion Well drilling operations.

In the application of Richard H. Carr et al., Ser. No. 90,784, now Patent No. 2,163,665, entitled Well drilling indicator and the application of Richard H. Carr et al., Serial No. 177,962 filed December 3, 1937, entitled Apparatus for use in connection with earth boring, there is disclosed apparatus for indicating the stresses in the line tools which occur during well boring and other well producing operations. From the line stresses obtained by means of the apparatus disclosed in those applications, it is possible to calculate the line stretch at any point during the stroke of the tools. However, in accordance with the apparatus disclosed in those applications, it is not possible to get an accurate picture of the motion of the drilling bit or other apparatus unless a diagram is plotted from calculations based on the stresses indicated by the apparatus. The length of the line or cable at the particular instant that it is subjected to a particular stress may be calculated according to the formula S L 181-2 X E where S1:Stretch of the line or cable in feet due to the particular stress. S :Stress in pounds. A :Cross-sectional area of the line or cable in square inches. L=Normal length of cable or line in feet when not subject to stress. E :Modulus of elasticity of the line or cable.

A diagram can be plotted showing S1 at each point in the up and down stroke of the line and beam to which it is attached. If to S1 for each point determined, is added or subtracted the distance moved by the end of the Walking beam, to which the line is fastened, a picture of the position of the drilling bit or other apparatus in the bottom of the hole can be obtained.

We have discovered that it is possible to indicate directly the motion of the drilling bit without resorting to calculations. Since the stretch in the line is directly proportional to the stress on the line Within the elastic limit of the line, the drilling bit will move downwardly with increased stress on the line and upwardly with decreased stress on the line, assuming the beam is stationary. Thus, by recording or indicating increased stress by vertical downward motion and decreased stress by vertical upward motion, a true indication of the motion of the drilling bit is obtained. If the motion of the drilling bit, as thus determined, is superimposed on the motion of the beam end to which the drilling string is attached, a true picture of the actual motion of the drilling bit will be obtained.

In accordance with our invention we have provided apparatus by means of which the varying stresses in the drilling line are transmitted by a suitable dynamometer to a pressure responsive mechanism connected to an indicator which moves in a vertical direction. This indicator and pressure responsive mechanism is so arranged that when the line tension increases, and consequently the pressure on the pressure responsive means increases, the indicator moves vertically downward, and when the tension and pressure decreases, the indicator moves vertically upward. The indicator is mounted on a movable member which is adapted to be reciprocated by suitable means in harmony with the stroke of the beam to which the drilling tools are connected. The movable member is adjustable so as to reciprocate along a straight line corresponding to a curve plotted with distance moved by the beam from one end of its stroke to the other end as ordinates, and degrees of a semi-circle projected onto a straight line as abscissae, assuming each stroke of the beam corresponds to one hundred eighty degrees. Thus the indicator is simultaneously subjected to the motion caused by reciprocation of the beam and the motion caused by the varying tension in the drilling string of tools. As a result the indicator will move in substantially the same manner as the drilling bit moves at the bottom of the well and the operator is able thereby to determine how effective the operation is and can make suitable adjustment from time to time to obtain optimum conditions of operation.

One of the objects of our invention is to provide means for determining the motion of well drilling or other well operating tools.

Another object of the invention is to provide apparatus whereby the motion of a drilling bit or other well operating tool, which is not visible, can be reproduced.

Another object of the invention is to provide means for enabling the control of well drilling or other well operations and for rendering such operations more efficient.

Further objects of the invention will become apparent from the following description and accompanying drawings, of which,

Fig. 1 is a front elevational view of' apparatus in accordance with our invention, with a portion thereof cut away.

Fig. 2 is a front elevational view of the apparatus shown in Fig. 1 but in a different position.

Fig. 3 is a plan view of the apparatus shown in Fig. 1 with parts thereof removed.

Fig. 4 is a front elevational view of a portion of the apparatus shown in Figures 1 and 2.

Fig. 5 is a vertical cross-sectional view taken on the line 55 of Fig. 1.

Fig. 6 is a vertical cross-sectional view of the gear box forming part of the apparatus shown in Figures 1 and 2.

Fig. 7 is a horizontal cross-sectional view taken on the line 1-1 of Fig. 6.

Fig. 8 is a vertical cross-sectional view taken on the line 88 of Fig. 7.

Fig. 9 is a graph showing the paths described by the beam and the drilling bit during percussion well drilling operations.

Referring more particularly to Figures 1 to 3, numeral I indicates generally a frame, the parts of which are preferably cast from steel or aluminum alloy and assembled so that it is rectangular in shape. The frame may consist of ends 3 and 5 which are held in spaced relation by means of tie bars I; The left end 5 of the frame is provided with vertical flanges 9 to which the plates II, having arcuate edges I3, are adapted to be bolted by means of bolts I4. The plates II are provided, adjacent the edges I3, with suitable holes I5. The arcuate edge I3 has a radius R (Fig. 1). The frame may be covered by suitable plates of steel or aluminum and the front plate is preferably provided with a frosted glass window (not shown) in front of the indicator, to be subsequently described.

Mounted in the frame adjacent the front thereof are the parallel rails I! and I9. The rails are held in spaced vertical relation by means of the tie bars 2| and 23. The lefthand ends of the rails are fastened to the plates II at the points 25 and 21 by means of nuts and bolts 28 passing through the holes I5. The rails are pivotally supported adjacent the right hand ends thereof by means of the shaft 29 passing through the tie bar 2| intermediate the ends thereof. Copper conductor bars 3| and 33 are fastened to the lower rail I9 and suitably insulated therefrom and from each other. The bars are connected by wiring to the batteries 35 or other suitable source of electric current. The rails I1 and I9 have longitudinal grooves 31 facing each other for the purpose of permitting the rollers 39 of the carriage frame 4| to ride therein.

The carriage frame 4| is preferably cast out of aluminum alloy for purposes of lightness. As shown in Fig. 4, the frame is cast with the openings 43 in order to add to its lightness. The radial arms 45 extend from points adjacent the outer edges of the carriage frame to the center thereof, where they join together to form hub 41. Although as shown in Fig. 4, the carriage frame is substantially square, it may be rectangular or other shape. The rollers 39 are ball bearing and mounted on pins 49, hammeror shrink-fitted into the carriage frame 4| adjacent the corners thereof. These rollers are adapted to freely roll in the grooves 31 of the rails I1 and I9 and maintain the carriage in place on the rails.

A steel pin or shaft 5| (Fig. 5) is hammeror shrink-fitted into the hub 41 of the carriage frame 4|. A rotatable disc 53, preferably of smaller diameter than the distance between the rails, is mounted at its center on pin 5| by ball bearings. The disc 53 is provided adjacent its lower edge with gear teeth 55. A worm 51 mounted on the carriage frame by means of bracket 59 is adapted to engage the gear teeth 55. The pinion may be rotated by means of a handle 6|.

A cylinder housing 63, having flanges 64, is rigidly mounted on the upper part of the disc 53 by means of bolts 55 passing through holes in the flanges. The upper end of the housing 63 is provided with a hollow, internally threaded coupling 61 to which a flexible hose is adapted to be connected. A cylinder 68 fits snugly within the housing 63. A slidable plunger 69 is snugly mounted in the cylinder 68 and is provided with an integral collar 'II intermediate the ends of the plunger. The lower end of the housing 63 is provided with an opening I3 through which the lower end of the plunger 69 passes. The diameter of this opening is smaller than the diameter of the collar II. The collar is mounted between the lower ends of the housing 63 and the cylinder 68 and limits the movement of the plunger in either direct-ion.

Referring more particularly to Figures 1, 2 and 3, bracket I5 is rigidly mounted on the upper right hand side of the disc 53. Bracket I5 is formed with bifurcated arm 11. The inner faces of the bifurcation are machined to receive the upper end of the arm I9 and an intermediate portion of the arm 8|. A pin 83 is rigidly mounted in the bifurcated arm 11 and the arms I9 and 8| are pivotally mounted on the pin by means of ball bearings. The arm 8| is also pivotally connected at the point 85 to the upper end of a rod 81. The rod 81 is vertically mounted directly below the plunger 69 and the lower end thereof is slidably mounted in the cylinder 88 which in turn is threaded into swivel bearing 89. The bearing 89 is held in place on the disc 53 by means of the bracket 9|. The lower protruding portion 92 of the cylinder 88 is hexagon or other suitable shape to permit it to be engaged by a wrench and be turned thereby adjusting the tension of coil spring 93. The calibrated coil spring 93 is mounted on the rod 81 between lip 95 and the upper face of the cylinder 88. The lower end of the plunger 69 is adapted to contact the roller 96 mounted on the pin 85.

A link 91 pivotally connects the left hand end of the arm 8|, by means of pin 98, to another link 99. The link 91 is pivotally connected to the link 99 intermediate the ends thereof by the pin NH. The link 99 is pivot-ally connected by means of pin I02 at the end I93 to the bar I05 which is vertically and rigidly mounted on the disc 53 at the points I81 and I09. The bar I95 is spaced from the face of the disc 53 by means of pins III. The indicator arm H3 is pivotally fixed to the other end of the link 99 by means of the pin H5 and is also pivotally fixed to the end III of the arm I9 by means of the pin 9. The indicator arm I I3, as shown in Fig. 3, is cast integrally with the spaced arm I2I. The various links and arms heretofore described are arranged between the inner arm I2I and main arm of the indicator arm I I3, and the various pins connecting the indicator arm to the several links and arms pass through both arms of the indicator.

All pivots are ball bearing mounted. It will be seen that the only fixed pivots are the pins 83 and I92. The linkage shown and described is so arfirst ranged as to cause the end I23 of the indicator H3 to move along a vertical line when motion is imparted to the rod 81. Light socket I 25 is mounted on the end I23 of indicator H3 and is adapted to receive a small electric light bulb. The socket I25 is adapted to be connected by suitable wires (not shown) to contact points or brushes I21 and I29 (Figs. 1 and 2) and in turn are connected to the brushes I3I and I33 which contact the copper bars 3| and 33. The brushes and contact points are located in the bracket I 35, fastened to the lower end of the carriage frame 4|.

Referring again to Figures 1 to 3, the left hand end of a connecting rod I31 is pivotally mounted on a pin I39, which is hammeror shrink-fitted into the left hand end of the carriage frame intermediate the upper and lower ends thereof and extends horizontally from the back face thereof. The right hand end of the crank arm is pivotally fixed to one end of a crank MI by means of pin'l43. The other end I45 of the crank is suitably weighted for counter-balancing purposes.

Referring more particularly to Figs. 3, 6, 7 and 8, a gear box I46 is suitably mounted by means of bolts I41 on brackets I49 formed integrally with the frame end 3. A shaft I5I extends horizon- .tally into the gear box through the housing I53 in which is mounted the bearing I55. The shaft is also supported by bearing I56. To the outer end of the shaft I5I is keyed a sprocket I51 by means of key I59. On the inner end of the shaft I5I is fastened a gear I6I which is adapted to rotate with the shaft. A horizontal shaft I63 in the same horizontal plane as the shaft I5I by running perpendicular thereto is mounted in the gear box in the bearings I65 and I61. One end 29 of the shaft I 63 extends outside of the gear box and the crank MI is keyed thereto or otherwise rigidly mounted thereon. A gear I1I is rigidly mounted on the shaft I63 inside the gear box adjacent the inside wall of the box and is adapted to engage the gear IBI. A second gear I13, smaller than the gear "I, is mounted on the shaft I63 adjacent the opposite wall of the gear box. This gear does not engage the gear I6 I. A vertical shaft I mounted in bearings I11 and I19 and held in place by retaining nut I89 extends into the gear box and has a gear I8I rigidly mounted on the inner end thereof. The gear I 8I is adapted to engage the gear I13. The upper end I83 of the shaft I15 extends through an opening in the upper part of the gear box. The opening is closed by a cap I85 secured to the box by means of bolts I81. A suitable pipe I89 having a cap I9I is screwed into the lower portion of the gear box in order to permit introduction of lubricant.

The tie bar 2I is pivotally mounted on the outer end 29 of the shaft I63.

The apparatus just described is used in the following manner: A sprocket is placed on the driving shaft of a well drilling rig (not shown) and the sprocket I51 is connected thereto by means of a chain (not shown). The coupling 61 at the top of the cylinder 63 is connected by means of a flexible hose or line to a dynamometer head fastened to the end of the walking beam of a well drilling rig. The drilling string or other string of tools is suspended from the dynamometer in a manner similar to that shown and disclosed in the aforementioned application, Carr et a1. Ser. No. 90,784, or the patent to Lake 1,739,724. The rotation of the drive shaft causes rotation of the shaft I5I and in turn of the crank I4I. As the crank rotates it causes the carriage to reciprocate on the rails I 1 and I9. At the same time the variation in tension on the string of drilling or other tools will be imparted to the plunger 69 and the rod 81 against the tension of the spring 93. Through the linkage heretofore described, the end I23 of the indicator II3 will be caused to move along a vertical line. Due to the simultaneous motion imparted to the carriage carrying the indicator arm and the motion imparted to the end of the arm by the variation in tension in the string of tools at each portion of the stroke of the string, the end of the indicator arm will define or trace the outline of an indicator card showing the tension at each point in the stroke of the drilling string.

As will be seen, increase in tension in the line will cause a downward movement of the end of the indicator arm and decrease in tension will cause upward movement. Since the change in length of the line is directly proportional to the tension in the line, the motion of the arm can be calibrated so as to indicate the exact change in length of line from point to point in the stroke. The path of the light bulb in the end of the indicator I I3 may be observed through a frosted glass window (not shown) placed in the frame cover plate. The size of the glass should be sufficient to provide vision of the light bulb at all times. In apparatus of this nature, a window approximately ten inches square will provide sufficient area. Thus the operator is enabled to continuously watch the path of the light bulb and determine Whether the tools are moving in the same direction as the end of the walking beam to which they are fastened, or are moving out of harmony therewith.

As shown in the graph in Fig. 9, the beam end movement through each one hundred eighty degrees durin the up and down strokes is represented by the line 0-0. During the up stroke of the beam, when the crank moves through an arc of one hundred eighty degrees, the beam moves upward from O to 0. During the next one hundred eighty degrees of revolution of the crank, the beam moves downward from 0 t0 0. If the tracks I1 and I9 are left in the horizontal position, shown in Fig. 1, the light bulb will trace a path indicated by the line A B C D E F G A. This diagram indicates that on the down stroke of the beam the drilling bit descended more slowly than the beam along the A G and that when the beam began its upward stroke the tension of the line suddenly increased and as a result the line stretch caused the tools to drop the distance A B. At the point B, the tools suddenly rebounded to the point C and then stretched again to the point D, rebounded upwardly to the point E, then stretched slightly to the point F, when the beam. was almost at the top of the stroke and then when the beam reached the top of the stroke the line again contracted until the drilling bit was at the position G. Although this diagram represents the stretch and contraction in the drilling line from time to time, it does not represent the exact position of the drilling bit at any point in the beam stroke. In order to obtain these observations it is necessary to rotate the tracks about the pivot 29 until the position of the track is on an angle corresponding to the angle between the horizontal line X-Y and the curve 0-0, indicating the beam movement. By doing this the distance the tools are moved, due to movement of the beam, is either added to or subtracted from the distance the tools move due to stretching or contracting of the line. After the track has been rotated to the required position and fastened in place on the plates H, the disc 53 is rotated by means of the worm 51 and handle 6| to a position such that the direction of movement of the end [23 of the indicator 3 is in a vertical direction when the carriage is motionless. When the apparatus is so adjusted, the path traced by the light bulb is represented by A" B C" D" E" F" G" A". This curve represents the position of the drilling bit at each point in the stroke and, thus, the position of the drilling bit at each point in the beam stroke can be accurately observed and the operator can determine whether or not the bit is striking bottom and when it strikes bottom. By proper adjustment of the speed and motion of the walking beam, the operation can be improved so that the bit strikes bottom at the bottom of the beam stroke and full impact of the stroke is obtained. By calibrating the spring 93 and the extent of motion of the carriage 4|, it is merely necessary to measure the height of any point of the curve from the bottom point and multiply by the scale factor in order to determine the actual distance the drilling bit moves from one point to the other.

The length of the line OO' corresponds to the distance which the carriage moves in either direction and its horizontal projection X-Y is divided into 180 as shown. The distance O-Y corresponds to the beam stroke and is drawn to the scale which corresponds to the calibration of the coil spring 93. For example, if coil spring 93 is calibrated so that for a line stress producing a stretch of one foot in the line the spring 93 will permit a vertical movement of one inch by the indicator bulb I25, then each inch of the distance Y will represent one foot distance of travel of the beam, so that when the movement caused by the line stress is superimposed on the movement of the beam, the two will add together in the same units and by merely multiplying the resulting distance by twelve, the number of inches of movement of the tool at the bottom of the well can be determined.

It is apparent that any scale can be used, but in the example just given in order to determine the distance in inches from the diagram, the scale factor would be twelve. From the distance the end of the beam travels during a stroke and the distance the carriage travels on each stroke, the angle between the line O--O' and O'-Y can be determined and the carriage then rotated to this angle.

When the carriage is rotated to the required angle, it will represent the height of the beam at each point in the stroke on the reduced scale. Therefore, when the stretch of the line is added to the height of the beam at any point, the position of the tool at the bottom of the well is precisely shown by the indicator. As previously pointed out, the diagram showing the position of the tool is represented by the letters A" B" C" D" E." F" G" A. It will be seen from this diagram that in this particular case the lowest point of the drilling bit, namely, B does not occur at the lowermost point of the beam stroke which is represented by the point 0, but occurs some time during the upward stroke of the beam. In a normal drilling operation the line is shorter than that which would be required in order for the drilling bit to rest on the bottom of the hole when the beam is at its lowermost position. It is only when the beam starts on its upward stroke and increased tension of the line causes stretching that' the bit goes downwardly and strikes bottom. Thus, at point A" which is the point of lowermost position of the beam, the bit is not on bottom. When the beam has travelled upwardly a distance corresponding to approximately 40, the bit hits bottom. The line then rebounds as shown at C and again stretches to D", whereupon it rebounds again to E and stretches slightly to F". The drilling bit is at its highestmost position G at the end of the upward stroke of the beam. The jagged line B" C D E" F" is caused by the bouncing of the line during the upstroke of the beam.

The measurements of height are taken from the lowestmost point B" where the tool strikes bottom. It will be seen that the vertical distance from the point B" to the point G" is greater than the distance from the point 0 to Y and the difference in distance is the distance which the line stretches in order for the tool to hit bottom. The bottommost point on the diagram OXY was drawn adjacent to the diagram A" B" C" D" E" F" G" A" merely to show how closely the downstroke of the diagram G" A" corresponded to the plotted stroke of the beam.

In order to obtain a permanent record of the motion of the drilling tools, the cap I85 may be removed from the gear box and a suitable recording device (not shown) may be fastened to the upper end of the shaft I15. This indicator may be connected to the dynamometer by suitable hose or line and a permanent chart record thus obtained of the stretch of the drilling or other line at each point in the stroke thereof.

Instead of using the chain drive from the drivin shaft to operate the device, the shaft I! may be connected directly to the walking beam and instead of turning the crank I39 through a complete revolution, the crank may oscillate back and forth. If desired, the gear box may be dispensed with entirely and suitable connections from the walking beam or drive shaft of the drilling rig 3 of the crank arm l4! made in order to oscillate the arm.

Instead of providing holes in the plates ll along the edge in order to adjust the position of the tracks, the plates may be furnished with an arcuate track adapted to engage gear wheels fastened to the tracks and the tracks can be moved into position in the same manner as the disc 53 is rotated.

The entire casing containing the device shown and described may be approximately three to four feet long by one and one half to two feet wide and the same height. By using light ma terials in the construction thereof the entire apparatus may be made to weigh from one hundred to one hundred fifty pounds so that it can easily be conveyed from place to place.

It will be seen that we have provided novel apparatus for indicating and observing the motion of a drilling bit, or other well operating tools, which is subjected to reciprocating motion, thereby eliminating the uncertain and undependable methods heretofore used in controlling and regulating such operation.

What we claim is:

1. Apparatus for reproducing motion of a tool connected to the lower end of a substantially Vertical, reciprocating, elastic line which comprises means for translating increase in line stress into vertical downward motion or for translating decrease in line stress into vertical ILO l HJUM upward motion, means for translating the reciprocating motion of the line into motion corresponding to a curve plotted with the distances the upper end of the line moves during each stroke as ordinates and degrees of a semi-circle projected onto a straight line as abscissae, assuming that each stroke of the line corresponds to one hundred eighty degrees, and means for producing a visual diagram of the combined effects of the two motions.

2. Apparatus for reproducing motion of a tool connected to the lower end of a substantially vertical, reciprocating, elastic line which comprises a carriage mounted on tracks and adapted to reciprocate thereon, means for reciprocating said carriage, means for rotating said tracks and said carriage in order to enable the carriage to reciprocate along a line at an angle to the horizontal, an indicator mounted on said carriage, a fluid pressure responsive means connected to said indicator in such manner as to cause said indicator to move in a straight line, and means to enable said indicator to be adjusted to move in a straight vertical line, regardless of the position of said carriage.

3. Apparatus for reproducing motion of a tool connected to the lower end of a substantially vertical, reciprocating, elastic line which comprises a carriage slidably mounted on tracks, means for reciprocating said carriage, means for rotating said tracks from a horizontal to an angular position in the same vertical plane, about a fixed axis, a rotatable disc mounted on said carriage, means for rotating the disc, an indicator mounted on the disc, and pressure respon sive means mounted on said disc and connected to said indicator in such manner as to impart straight line motion thereto.

4. Apparatus for reproducing motion of a tool connected to the lower end of a substantially vertical, reciprocating, elastic line which comprises means for translating increase in line stress into vertical downward motion or for translating decrease in line stress into vertical upward motion, means for simultaneously translating the reciprocating motion of the line into motion corresponding to a curve plotted with the distances the upper end of the line moves during each stroke as ordinates and degrees of a semi-circle projected onto a straight line as abscissae, assuming that each stroke of the line corresponds to one hundred eighty degrees,

means for superimposing the translated line stress motion upon the translated reciprocating motion of the line and means for obtaining a Visual diagram of the superimposed motions.

5. Means for automatically and visually reproducing the motion of a subterranean tool connected to the end of a substantially vertical, reciprocating, elastic line which comprises means for translating stress at each point in the stroke of the line into straight line motion at the surface of the earth, proportional to the stretch of the elastic line produced by the stress, means for translating the reciprocating motion of the elastic line into straight line motion corresponding to a curve obtained by plotting in the direction of the straight line motion into which the stress is translated, distance moved by the upper end of the elastic line, and by plotting at right angles with said direction, degrees of a semi-circle projected onto a straight line, means for superposing the straight line motion corresponding to the stretch of the elastic line on the motion corresponding to the reciprocating motion of the elastic line and means for producing a visual diagram of the combined effects of the two motions.

6. Apparatus for reproducing motion of tools located in earth bores and connected to a substantially vertical, reciprocating, elastic line which comprises a carriage slidably mounted on horizontal tracks, means for reciprocating said carriage, means for rotating said tracks about a fixed axis to an angular position in the same plane, a rotatable disc mounted on said carriage, means for rotating said disc, an indicator arm pivotally mounted on said disc, a series of interconnected links mounted on said disc and connected to said arm in such manner that movement of said links imparts substantially straight line motion to the end of said indicator arm in a plane parallel to the plane in which the carriage is adapted to reciprocate, a cylinder adapted to be connected to a source of fluid pressure, mounted on said disc, a piston slidably mounted in said cylinder, one end of said piston extending outside of said cylinder and adapted to operatively engage said links, and a coil spring mounted on said disc in a position to oppose the movement imparted to said links by said piston.

YOUNGER NEAL. GLEN G. I-IEZBARD. 

